1. Field of the Invention
This invention relates to a pressure gauge which has a dial with a pointer to show the results of measurement of the pressure gauge.
2. Description of Background Art
Pressure gauges or the type described above are commonly used in measurements of pressure in pipelines, pressure containers, etc. Many improvements have been made by the applicant of this invention. FIGS. 1A and 1B show one of the improved pressure gauges which is provided by the applicant. The pressure gauge is characterized in that: (1) The conventional straight piston rod is changed to a U-shaped rod A to reduce the size of the pressure gauge, the U-shaped rod having rack teeth al at one end and a screw thread a2 at the other end to be connected threadedly with a piston B; (2) the conventional pressure chamber body is substituted by a body C which is connected with a channel-like guide piece D; and (3) the conventional positioning body and plate to hold a transmitting gear of the pointer is substituted by an L-shaped plate E. This pressure gauge has a reduced size and reduces the risk of malfunctioning as well as the risk of causing errors in measurement.
FIG. 2 shows a second pressure gauge of the applicant which is improved to eliminate the defect found in the pressure gauge of FIG. 1 such as that the chuck G and the sealing member H provided in the tubular pressure chamber body C must be removed in case the pressure gauge is adjusted. In the second pressure gauge, the bottom T of the tubular pressure chamber body C is hollowed and provided with an internal screw thread t1, receiving an adjustment screw cap S with a diametrical bottom groove s1, so that adjustment can be made by turning the screw cap S. However adjustment of the pressure gauge must be accomplished by removing the housing from the pressure gauge.
FIG. 3 shows a third pressure gauge whose air intake port is provided at an end face Q of the housing and whose pressure chamber body C is provided with an inner tubular member P to receive a piston. An air passage R is provided between the walls of the inner tubular member P and the outer hollow body C to permit air to enter the inner tubular member P from the air intake port.